Washington
— The United States has sustained ``immense'' damage to its national security as a result of Soviet and other espionage efforts in recent years, and it continues to face a serious ongoing threat, according to a congressional study released Tuesday. In the US government's first comprehensive public assessment of the effects of recent spy cases -- including those of John Walker, Jerry Whitworth, and Ronald Pelton -- the Senate Select Committee on Intelligence says that hostile intelligence operations have done more damage to US security than previously disclosed.

``The committee has found the aggregate damage in recent years to be far greater than anyone in the US government has yet acknowledged publicly,'' the report says.

The study notes that ``espionage cases over the past several years have involved billions of dollars of actual and potential damage to US military programs.'' In addition, the report says Soviet acquisition of sensitive technology has reduced from 10 years to five years the West's technological lead over the Soviet Union.

The unclassified report is the result of 16 closed-door Senate hearings with US intelligence officials and a governmentwide staff investigation conducted over an 18-month period. The report's 95 recommendations and findings are aimed at helping the US develop a national strategy to counter Soviet and other spying operations here. A more detailed classified version of the report is being circulated within the intelligence community.

``The hostile intelligence threat to America's security is greater than ever before,'' says Sen. Dave Durenburger (R) of Minnesota, chairman of the Senate Intelligence Committee. ``The Soviet Union and other countries devote many billions of dollars to their efforts to spy on us. And they get billions of dollars in benefits in return for their efforts.''

Committee vice-chairman Patrick J. Leahy (D) of Vermont says, ``There is no way you can pass a law that [will prevent] all spying, but you can certainly take steps to make spying more difficult and make it easier for us to protect our secrets. The national security is many times more threatened by [espionage] than by the development of Soviet arms, by the buildup of Soviet personnel, or by a breakthrough in weapons development.''

Among the committee's recommendations:

Limit the number of Soviet diplomats and officials stationed in the US to enable American counterintelligence agents to watch them more closely.

Expand current travel and other restrictions that apply to Soviet diplomats to diplomats, officials, and commercial representatives from other Soviet-bloc nations stationed in the US and at the United Nations.

Reduce the number of foreign nationals employed in US embassies (particularly the US Embassy in Moscow) and on military bases overseas.

Establish a uniform policy of background checks and security safeguards for government workers, private-sector contractors, and industry officials working in sensitive areas.

Beef up US countermeasures against Soviet efforts to intercept a broad range of American communications.

The Senate report includes a case-by-case damage assessment of recent spying. Information in the appendix of the report says that the Soviets considered the Walker-Whitworth spy operation ``to be the most important operation in the KGB's history.''

The statement is contained in an affidavit submitted by John L. Martin of the Justice Department in the Whitworth spy case last August. It relates information learned from Soviet defector Vitaly Yurchenko about the Walker spy ring. Mr. Yurchenko, who defected to the US in July 1985 and then re-defected to the Soviet Union several months later, had served as a high-ranking KGB counterintelligence officer. In that capacity, he had been briefed by KGB officials on the Walker spy operation.

``Yurchenko stated that the information delivered by Walker enabled the KGB to decipher over 1 million messages,'' Mr. Martin said in the affidavit. Martin added, ``Yurchenko was informed by a high KGB official that the information from the Walker-Whitworth operation would have been `devastating' to the United States in time of war.''

US naval intelligence has reached a similar conclusion about the consequences of the Walker-Whitworth spy operation. ``Naval intelligence analysis has led us to conclude that the Walker-Whitworth espionage activity was of the highest value to the intelligence services of the Soviet Union, with the potential -- had conflict erupted between the two superpowers -- to have powerful war-winning implications for the Soviet side,'' says William O. Studeman, director of naval intelligence, in an affidavit submitted in the Whitworth case and included in the appendix of the Senate report.

Mr. Studeman noted, ``Recovery from the Walker-Whitworth espionage will take years and millions of taxpayers' dollars. Even given these expenditures, we will likely never know the true extent to which our capabilities have been impaired....''

Jerry Whitworth, a former Navy communications officer, was found guilty last summer of spying for the Soviets and was sentenced to 365 years in prison and fined $410,000. John Walker, who has said he masterminded the Soviet spy ring that included Walker's brother, his son, and Whitworth, is awaiting sentencing.

In a broad sense, the Senate Intelligence Committee's report is aimed at raising the nation's awareness of the threats posed by hostile intelligence operations in the US. And it is intended in part to foster continued public support for major funding programs designed to bolster American security and counterintelligence.

The report notes that while the nation's counterintelligence structure is fundamentally sound, ``particular elements need to be strengthened.''

In recent years, Soviet spy efforts have grown larger, more determined, and more sophisticated. In the past two years, 25 people have been convicted or pleaded guilty to spying in the US. Many of the cases have provided important insights into the failings of US security policies.